I wouldn't hold my breath for this yet.
Unless Austin and NJ will be like Nurburgring and Hockenheim, hosting Grand Prix of United States in alternate years? That's probably why they propose to be 2013. Where Austin to be 2012.

Who knows? I recall Bernie and FOTA both mentioning that the goal is to have 'multiple' grand prix in the United States. The question is whether there is demand for more than one grand prix a year...and I'm not sure, unless they can really raise the popularity of the sport here.

The idea itself isn't bad. There's a large international community on the east coast, and quite a large F1 community in this area. Plus, the draw for the circuit will be having one of the largest tourist centers in the United States just minutes away.